Tubing joint

ABSTRACT

A tubing joint comprises a grip-ring whose grip-nails bite the outer wall of a tubing inserted into the joint proper to prevent the inserted tubing from moving in the tubing-detaching direction, and a release-ring which releases the bite of the grip-nails on the outer wall of the inserted tubing. The grip-ring is formed in a zigzag ring having a number of notches cut radially and alternately from the inner and outer circumferences of the ring. The outer extremity side of the grip-ring is bent by a constant width in the tubing-admitting direction and the bent ends, i.e., outer extremities, are inserted into a catching section to hold the grip-ring within the joint proper. The inner extremities of the grip-ring formed by the notches serve as grip-nails.

DESCRIPTION OF THE PRIOR ART

Various structures have been devised for tubing joints which connectflexible tubings for transferring liquids with each other.

In conventional tubing joints, several, say four, lock nails areprovided on the inner wall of joint at regular intervals along acircumference with such a slant positioning that each nail is directedforward from the tubing-admitting opening. When a tubing is inserted,the tips of each nail are pushed outward by the wall of the tubing, andwhen a tubing once inserted is caused to move in the tubing-withdrawingdirection, frictional force, etc. will allow the lock nails to bite theouter wall of tubing to prevent the disengagement of the tubing. Toeffect the withdrawal of tubing, the tubing joint is provided withreleasing means such as a release-ring which is designed to push thetips of lock nails outward to free the tubing from the biting action ofthe lock nails.

The above-mentioned conventional structure of tubing joints requires thelock nail itself to be rigid to a considerable degree. To meet thisrequirement, thick materials have been used for the lock nail to providethe required rigidity and the form of the tip of lock nail has beensubjected to modifications, for example, into the form of a sharp bladeto promote its capability of biting the outer wall of tubing.

The above-described structure using lock nails of high rigidity but lowelasticity has a disadvantage in that, when the blade of lock nailhappends to begin sliding on the outer wall of the inserted tubing, thelock nail will be hard to adjust itself to the movement of tubing,resulting in a lowered degree of bite onto the tubing. This disadvantageis increased when the tubing is made of a relatively hard material. Itis true that a lock nail, when made thin, is capable of adjusting itselfto the movement of tubing, but such nails are low in rigidity.

The present inventor has devised a grip-ring (Japanese PatentApplication No. 56-177664), as shown in FIG. 1, effective to eliminatethe above disadvantage, for which a plate of an elastic material such asphosphor bronze is punched to give a ring and a number of notches 1 and2 are cut radially out alternately from both inner and outercircumferences.

The above-described grip-ring 3, as shown in FIG. 2, is caught by agroove 6 on a guide-ring 5 in a joint proper 4 so that the innerextremities of grip-ring 3 having notches 2 formed may bite the outerwall of an inserted tubing 7. An elastic sleeve 8 is designed to comeinto contact with the inner extremities from inside the joint tosupplement the elasticity of the inner extremities. A release-ring 9 ispushed in the longitudinal direction for withdrawal of tubing 7, therebypushing out the inner extremities of grip-ring 3.

Grip-ring 3 is in a zigzag ring as shown in FIG. 1 and thus, when tubing7 is inserted to push out the inner extremities, the strong springproperty peculiar to the unique zigzag form will produce various forcessuch as a torsional reactional force near the inner extremities in thetubing-inserting direction. Thus, even with a thin grip-ring 3, a strongspring property may be displayed by support of the supplement ofelasticity from elastic sleeve 8. It should be noted that the springproperty thus displayed is a so-called viscous spring property incontrast to the one produced by conventional grip-rings; thus, thegrip-ring may adjust itself readily to even a slight movement of theinserted tubing in the tubing-withdrawing direction, biting the outerwall of the tubing for effective tubing retention, and after thegrip-ring once bites the outer wall of tubing, unnecessarily strongerbite power will no longer be produced, i.e., no increase in depth of onthe outer wall of tubing may occur with lapse of time.

The above-described grip-ring 3, though having many advantages, has beenfound to have the following inherent disadvantage which stems from itsplanar form: As tubing 7 is pushed in, the inner extremities ofgrip-ring 3 are caused to expand with the outer extremities as fulcrumsand the planar form of grip-ring 3 will result in expanding the effectof this local deformation over the entire grip-ring 3. To explain inmore detail, when an insertion of tubing has expanded the innerextremities, the tensile force, etc. acting on the zigzag connectedsections will, on the one hand, cause the notches 2 of the innerextremities to expand and, on the other hand, cause the notches 1 of theouter extremities to shrink. Thus, when the inner extremities have beenpushed out, the outer diameter of the outer extremities decreases. Forsuch a sequence, an insertion of tubing 7 will cause a positionaldeviation of the fulcrum of the outer extremities within groove 6, whichreduces the angle between the inner extremities and the outer wall oftubing 7, with lowered bite of inner extremities ont the outer wall oftubing 7, or which often causes diengagement of the outer extremitiesfrom groove 6.

Another problem has been experienced in the application of release-ring9 to detaching tubing 7, as follows: Suppose that grip-ring 3 has bittenthe outer wall of tubing 7 at the above displaced position, under whichcondition grip-ring 3 is at a deeper position and with a moredeformation and a greater tilt than is prescribed. Under such acondition, to use release-ring 9 to release the bite of grip-ring 3,release-ring 9 needs to be pushed in further beyond the prescribedposition, which will result in disturbed detachment of tubing or whichwill lead to unsuccessful detachment if some limit is imposed on theworking distance of release-ring 6. In addition, even if a releasing hasbeen effected by forcing the already-deformed grip-ring to deformfuther, grip-ring 3 has often been deformed too much beyond itselasticity limit for its re-use.

Still further problems has been experienced in cases elastic force ofgrip-ring 3 has allowed itself to return from the above-describeddisplaced position within groove 6 to the normal position with its bitekept on the outer wall of tubing 7: In this case return tubing 7 ispushed back in the tubing-detaching direction without being fixed at theprescribed position for insertion, resulting in leakage of liquid; whenrelease-ring 9 is pushed in for detaching the tubing, tubing 7 bitten bygrip-ring 3 will slightly be pushed in to the initial, prescribedposition for insertion and then release-ring 9 will begin to push outthe inner extremities of grip-ring 3, when the positional condition withrespect to the tubing, grip-ring, and release-ring is the same as thepreviously-described troublesome condition.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a tubing joint whichemploys a grip-ring of bent structure capable of displaying a strongspring property so as not only to be free of positional deviation of thegrip-ring but also to surely bite the outer wall of an inserted tubing.

Another object of the present invention is to provide a tubing jointwhich employs a stopper serving to prevent the grip-ring from gettingdeformed in excess of its elasticity limit so as to have a long servicelifetime.

A still further object of the present invention is to provide a tubingjoint which allows the grip-ring to have its grip extremities locked ata position slightly over the maximal bite position for the outer wall ofan inserted tubing so as to be capable of more secure biting on theouter wall of the inserted tubing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front view of a conventional grip-ring;

FIG. 2 is a sectional view illustrating the structure of a tubing jointwith the grip-ring of FIG. 1 incorporated;

FIG. 3 is an illustrative view for the operation of the tubing joint ofFIG. 2;

FIG. 4 is a sectional view of a tubing joint in accordance with thepresent invention;

FIG. 5a is a partial front view of a grip-ring;

FIG. 5b is a sectional view of a grip-ring;

FIG. 6 illustrates how to put the grip-ring into a guide-ring to formthe stopper wall for the inner extremities; and

FIG. 7 is a sectional view of another tubing joint in accordance withthe present invention.

SPECIFICATION OF THE INVENTION

The preferred embodiment of the present invention will be explained indetail with reference to the accompanying drawings.

Referring to FIG. 4, a joint proper 10 in an approximate cylinder isprovided on its inner wall with a first step 11, a second step 12, and athird step 13 at successively farther positions from thetubing-admitting opening with successive reductions in inner diameter. Aguide-ring 14 in an approximate cylinder is fixed inside joint proper 10with its collar 15 in contact with the first step 11. Guide-ring 14 isprovided, on its inner wall at its middle position, with a control step16 and, at its innermost position, with a circular groove 17. The secondstep 12 makes joint proper 10 equal in inner diameter to a nylon orpolyurethane tubing 18 to be inserted and, on the other hand, the thirdstep 13 sets in position the tubing 18 to be inserted.

An elastic sleeve 19, in an approximate cylinder made of an elasticmaterial such as rubber, is held between the second step 12 of jointproper 10 and guide-ring 14. Elastic sleeve 19 is provided at each ofits ends with angular relief grooves 20 and 21.

A grip-ring 22, as seen from FIG. 5, is prepared by punching a ring outof a thin (ca. 0.2 mm) plate of an elastic material such as phosphorbronze and by making a number of radial notches 23 and 24 alternatelyfrom the inner and outer extremities of the ring into a zigzag ring.

Grip-ring 22 has its outer extremities caught by circular groove 17 and,on the other hand, uses its inner extremities to bite the outer wall oftubing 18, thereby preventing the tubing from being disengaged.Grip-ring 22 has its outer extremities bent by a prescribed width towardthe tubing-admitting direction into a half-stretched L shape. The outerextremities, or bent ends, are positioned so as to be in touch with thecorresponding circular corner of circular groove 17 or with the wall ofcircular groove 17 extending from that circular corner.

A release-ring 25 in an approximate cylinder (FIG. 4) is in slidingcontact with guide-ring 14 and is movable in the longitudinal directionuntil its enlarged-diameter step 26 comes into touch with control step16 of guide-ring 14 or until its collar 27 comes into touch with thetubing-admitting side of guide-ring 14. Release-ring 25 has its innersection beyond enlarged-diameter step 26 tapered with reduced diametertoward the innermost end and thus, release-ring 25, when pushed in, willpush out, with its end, the inner extremities of grip-ring 22 towardelastic sleeve 19 and deform the inner extremity section of grip-ring 22into a conical form, with resulting release of the bite of grip-ring 22on the outer wall of tubing 18.

With the above-described structure, when the tubing 18 is inserted intojoint proper 10 through release-ring 25, it goes under the elasticforces of the inner extremities of grip-ring 22 and of elastic sleeve19, pushing outward the inner extremities of grip-ring 22, until it hitsthe third step 13. During this process, since grip-ring 22 has its outerextremities in contact with the corresponding corner section of circulargroove 17 or with the wall of circular groove 17 on the side of thatcorresponding corner section, the pressure exerted on grip-ring 22 fromthe insertion of tubing 18 is received by the corner section or wall viathe outer extremities corresponding to the bottom edge of a circulartruncated cone formed by the bent section of grip-ring 22; this circulartruncated cone is strong enough in shape to resist the pressure exerted.With conventional structures, when the inner extremities are pushed outwith resulting expansion of the intervals between notches 23, the outerextremities are caused to shrink in diameter with resulting displacementwithin circular groove 17. The present invention is effective toeliminate such a disadvantage since, when the intervals between notches23 are caused to expand, the intervals between notches 24 are alsocaused to expand contrary to conventional structures, because the outerextremities are designed to be in pressurized contact with theabove-mentioned corner section or wall of circular groove 17. Inaddition, with the structure in accordance with the present invention,the overall balanced force produced by the high strength of the bentgrip-ring sections, the above-mentioned action to expand both thenotches 23 and 24, etc. is capable, as shown in FIG. 4, of expanding theinner extremities outward about the base of the bent sections as afulcrum, in contrast to the conventional grip-ring which is expanded asa whole about the outer extremities of grip-ring. Thus, the deformedsection will have its diameter reduced so as to promote the biting ofgrip-nails on the outer wall of tubing 18, and, on the other hand, forthe withdrawal of tubing 18, release-ring 25, upon being pushed in, willrapidly release the bite of grip-nails on the outer wall of tubing 18.

FIG. 6 illustrates how to incorporate grip-ring 22 in circular groove 17on guide-ring 14.

The end section of guide-ring 14 is previously formed in a thin-walledcylinder. Grip-ring 22 is put into this cylinder with the prescribedpositioning and then the end section of the cylinder is pressed into awavy form to form circular groove 17, which keeps grip-ring 22 fromdisengagement.

The slant wall 17a at the pressed-in section of the cylinder serves toprevent the inner extremities of grip-ring 22 from being deformed beyondits elasticity limit.

FIG. 7 illustrates another embodiment of the present invention. Agrip-ring 22 is put in a circular groove 17 with the direction ofbending of the outer extremities coinciding with the admitting directionof tubing 18. Without tubing 18 inserted, grip-ring 22 is in the freestate where the inner extremity section is in a plane perpendicular tothe axis of the joint proper 10. A release-ring 25 has its outerdiameter reduced forward from an enlarged-diameter step 26 and itslength is so arranged that, when enlarged-diameter step 26 is in contactwith a control step 16, the front end of release-ring 25 is positionedjust in contact with the inner extremity face of grip-ring 22 or with ashort gap to the inner extremity face.

With the above-described structure, when tubing 18 is inserted intojoint proper 10 through release-ring 25, it goes under the elastic forceof the inner extremities of grip-ring 22, pushing outward the innerextremities of grip-ring 22, until it hits the third step 13. Duringthis process, tubing 18 being inserted will push grip-ring 22 but, sincethe outer extremities are bent in the direction for the insertion oftubing 18 or so as to press the inner wall of circular groove 17 underthe pressing force from tubing 18, grip-ring 22 will not displace withincircular groove 17 even under the pressing force from tubing 18, theinner extremities repeating to be expanded by a prescribed angle even byrepeated insertion of tubing 18. Therefore, the inner extremities ofgrip-ring 22 will come into contact with the outer wall of tubing 18with a prescribed tilt and bite the outer wall of tubing 18 by theaction of their elastic force, usually preventing the disengagement oftubing 18. In this stage the inner extremities are positioned at P (FIG.7). Now, tubing 18 is pulled back slightly in the detaching direction.The inner extremities biting the outer wall of tubing 18 will movetogether with tubing 18, making an arc movement about the outerextremities of grip-ring as the fulcrum. They will pass the maximum biteposition where the line connecting the outer and inner extremities isvertical to the outer wall of tubing 18 and finally reach position P(FIG. 4) where the inner extremities are positioned close to the frontend of release-ring 25 positioned with its enlarged-diameter step 26 incontact with control step 16. Position Q is slightly beyond the maximalbite position described above and the quantity of bite of the innerextremities onto the outer wall of tubing 18 is greater at position Qthan at position P, i.e., an adequate prevention of disengagement oftubing 18 is provided at position Q. If tubing 18 with position Qapplied is to be drawn out, the inner extremities will go practicallyvertically vertical toward the outer wall of tubing 18 without lettingtubing 18 slide out and, at the same time, the inner extremity face willbe controlled by the front end of release-ring 25 so as not to continuetheir arc rotation, i.e., the front end of release-ring 25 serves as astopper for the inner extremity face. On the other hand, if tubing 18with position Q applied is to be pushed inward, the inner extremitieswill never go to position P since the positional shift from Q to Prequires the maximal bite position of the inner extremities with respectto tubing 18 to be exceeded. Thus, the inner extremities are positionedat the same stable position as without tubing inserted, biting the outerwall of tubing 18 in a locked state with a preventive effect againstdisengagement of tubing 18.

As described above, the inner extremities of grip-ring 22 become lockedwhen they have passed slightly beyond their maximal bite position on theouter wall of tubing 18 to contact the front end of release-ring 25.Therefore, even when tubing 18 has been deformed from a straight to arcform before use, the inner extremities will never get displaced on theouter wall of tubing, or no spiral dented traces will be formed so as tocause the disengagement of tubing.

For the withdrawal of tubing 18, pushing release-ring 25 as it is willnot easily result in the required shift of the ring since grip-ring 22is locked. As a preparative step, tubing 18 is first to pushed in, whichwill easily return the inner extremities of grip-ring 22 from position Pto Q. The step is followed by pushing release-ring 25 in the usual way,which will release the bite of the inner extremities with resultingdetachment of tubing 18.

We claim:
 1. In a tubing joint assembly capable of releasably couplingwith a flexible tubing inserted in a tube-receiving end thereof, saidassembly comprising a tubing joint containing, a release ring, a guidering with a groove therein, a grip ring, and an elastic sleeve having arecess, the improvement wherein:(a) the grip ring is formed of aplurality of inner and outer radial notches cut alternately from itsinner and outer circumferences with the outer portion thereof beinguniformly bent in a tube-admitting direction to form an obtuse angle incross-section;(i) the bent outer portion thereof is inserted in theguide ring groove with the outer notches pointed away from thetube-receiving portion; (ii) the inner notches are pointed away from thetube-receiving portion to grip the surface of the tubing such thatlongitudinal movement of the release ring towards the inner notches willdisengage the inner notches from the tubing and move them into therecess in the elastic sleeve; (b) the release ring has a substantiallyuniform inner diameter which approximates the outer diameter of theflexible tubing to be coupled, and outer diameter portions whichcomprise, in sequence:(i) a relatively large outer diameter portionextending beyond the tubing joint to provide a gripping means foraxially sliding said release ring; (ii) a relatively small outerdiameter portion extending inwardly from said relatively large outerdiameter portion into said tubing joint for receiving a portion of aguide ring; and (iii) an intermediate outer diameter portion whichtapers to a wedge at the inner end of said release ring for axiallypressing against a grip ring to release it from engagement with aflexible tubing and move it against an elastic sleeve.
 2. A tubing jointassembly according to claim 1 wherein the tubing joint comprises, insequence:(a) a guide ring receiving portion having an increased diameterat the tube-receiving end thereof and a lesser inner diameter along theremainder thereof, the difference in diameters between said portionsforming a stop means for limiting the axial movement of a guide ringinto said tubing joint; (b) an elastic sleeve receiving portion havingan inner diameter corresponding to the lesser inner diameter of theguide ring receiving portion; (c) a tubing end alignment portion havingan inner diameter which approximates the outer diameter of a flexibletubing to be coupled but is less than that of the elastic sleevereceiving portion, the difference in diameters between said sleevereceiving portion and said tubing end alignment portion forming a stopmeans for limiting the axial movement of an elastic sleeve into saidtubing joint; and (d) a fluid passage portion having an inner diameterwhich approximates the inner diameter of the flexible tubing to becoupled, the difference in diameters between said fluid passage portionand said tubing end alignment portion forming a stop means for limitingthe axial movement of said flexible tubing into said tubing joint.
 3. Atubing joint assembly according to claim 1 wherein the guide ringhas:(a) an outer circumferential portion extending from the elasticsleeve along the inner wall of the joint to a first step at thetube-receiving end of said joint; and (b) an inner circumferentialportion having a guide ring groove near said recess for securing a guidering therein and a control step between it and the tube-receiving end ofsaid joint.
 4. A tube joint assembly according to claim 1, wherein theelastic sleeve has:(a) an outer circumferential portion extending from asecond step in the joint along the inner wall of the joint; and (b) aninner circumferential portion extending from a recess in the second stepalong the outer wall of the tubing and tapering radially outward towardsthe open end of the joint to form said recess for receiving the gripring during its removal.